1. Field of the Invention
The present invention concerns a control device for a switched power supply, namely a device designed to control a switching circuit in order to permit or prohibit the supply of a voltage, during very short periods, and in order to obtain, at the output of the switching circuit, a voltage with a mean value that is a function of a signal with an index value. This signal with an index value may be, for example, the output voltage of the supply or a signal representing a value to be obtained for this output voltage, or an adjusting signal which is a function, for example, of the temperature. The signal with an index value may also be a combination of signals such as this.
2. Description of the Prior Art
Power supplies comprising devices such as these are known: they make it possible to obtain adjustable or fixed DC voltages from other DC voltages or from rectified AC voltages They can also be used to obtain AC voltages from DC voltages.
Known control devices have an oscillator circuit and, generally, depending on whether the signal with an index value is greater or smaller than a reference value, the output signal of the oscillator circuit is applied or not applied to the switching circuit to turn it on or off.
These known devices have problems related to development and final fabrication: thus, non-linearity and lack of precision may give rise, inter alia, to insufficient stability, especially in the oscillator, and may create difficulties in making the output supply signal proportionate to a manual control acting on the set signal.